The present invention relates to a semiconductor large-scale integrated circuit having a central processing unit (CPU) and a digital signal processing unit, and more specifically to a technology suitably applied to data processing devices, such as microcomputers and digital signal processors, that require high calculation speeds.
An example of a microcomputer, which has mounted on a single chip the central processing unit (CPU) for controlling an entire system and the digital signal processing unit (digital signal processor (DSP)) having a product sum function required for efficient processing of digital signals, is found in "SH Series Incorporating DSP Function" by Kawasaki, et al., Nikkei Electronics, Nov. 23, 1992 issue, no. 568, pp. 99-112.
According to this literature, the digital signal processing unit having the product sum function is able to execute representative calculations of digital signal processing, such as digital filtering, efficiently in a small number of steps.